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ILS Ch 14
| Question | Answer |
|---|---|
| Work | apply force times distance, labeled in Joules |
| Power | labeled in watts or horsepower, work divided by time, rate of doing work |
| Machine | multiplies force, force and distance are inverse, can change direction of force |
| Work output | can not be greater than work input, increased by reducing friction or increasing work input |
| Mechanical advantage | output force divided by input force |
| IMA | problem, pulley |
| Friction | decreases efficiency |
| Efficiency | never 100%, always less, some input force always lost to friction, work output divided by work input |
| Inclined plane | increases distance, ramp |
| Wedge | 2 inclined planes, axe, as thickness increases IMA decreases |
| Wheel and axle | doorknob |
| Compound machine | includes more than one simple machine, bicycle |
| Force | only does work if it applied in the direction of the motion |
| Screw | inclined plane wrapped around a cylinder |
| Levers | 3 classes, gears are continuous levers |
| First class lever | fulcrum in middle |
| Second class lever | output force in middle |
| Third class lever | input force in middle, IMA always less than 1 |
| Math problems | work, power, efficiency, |